Marcel-Oliver Widi asked what work on semigroups in GAP (or perhaps in
computational semigroup theory) is ongoing.

We know about the work of Christof Noebauer, also at Linz, whose nrsg
package for near-rings (in gap/incoming) also contains some elementary
semigroup methods.

The latest version of Derek Holt's Knuth-Bendix package is called
KBMAG (Knuth-bendix for Monoids and Groups) and, as the name implies,
offers access to a (very fast) Knuth-bendix for monoids, and which
also offers some capabilities to compute with the resulting rewrite systems.

Edmund Robertson has posted a description of our work in St. Andrews
which will probably form the basis of semigroup support in GAP 4.
Semigroups will definitely be an important part of future versions of
GAP, and we welcome suggestions for or contributions to that.